Fukushima: Reactors and the Public

byPaul GilsteronMarch 14, 2011

All weekend long, as the dreadful news and heart-wrenching images from Japan kept coming in, I wondered how press coverage of the nuclear reactor situation would be handled. The temptation seemed irresistible to play the story for drama and maximum fear, citing catastrophic meltdowns, invoking Chernobyl and even Hiroshima, along with dire predictions about the future of nuclear power. My first thought was that the Japanese reactors were going to have the opposite effect than many in the media suppose. By showing that nuclear plants can survive so massive an event, they’ll demonstrate that nuclear power remains a viable option.

This is an important issue for the Centauri Dreams readership not just in terms of how we produce energy for use here on Earth, but because nuclear reactors are very much in play in our thinking about future deep space missions. Thus the public perception of nuclear reactors counts, and I probably don’t have to remind any of you that when the Cassini orbiter was launched toward Saturn, it was with the background of protest directed at its three radioisotope thermoelectric generators (RTGs) that use plutonium-238 to generate electricity. A similar RTG-carrying mission will doubtless meet the same kind of response.

What the public thinks about nuclear power, then, has a bearing on how we proceed both on Earth and in space. So how are the media doing so far with what is happening in Japan? Josef Oehmen, an MIT research scientist, has some thoughts on the matter. In an essay published yesterday by Jason Morgan, an English teacher and earthquake survivor who blogs from Japan, Oehmen gives us his initial reaction:

I have been reading every news release on the incident since the earthquake. There has not been one single (!) report that was accurate and free of errors (and part of that problem is also a weakness in the Japanese crisis communication). By “not free of errors” I do not refer to tendentious anti-nuclear journalism – that is quite normal these days. By “not free of errors” I mean blatant errors regarding physics and natural law, as well as gross misinterpretation of facts, due to an obvious lack of fundamental and basic understanding of the way nuclear reactors are built and operated. I have read a 3 page report on CNN where every single paragraph contained an error.

Reactor Basics and the Fukushima Story

What to do? Oehmen proceeds to go through the basics about nuclear reactors and in particular those at Fukushima, which use uranium oxide as nuclear fuel in so-called Boiling Water Reactors. Here the process is straightforward: The nuclear fuel heats water to create steam, which in turn drives turbines that create electricity, after which the steam is cooled and condensed back into water that can now be returned for heating by the nuclear fuel. Oehmen’s article, which I recommend highly, walks us through the containment system at these plants.

Image: Reactor design at Fukushima. Credit: BraveNewClimate.

The scientist also makes an obvious point that some in the media should probably take note of. We are not talking about possible nuclear explosions here of the kind that happen when we detonate a nuclear device. For that matter, we’re not talking about a Chernobyl event — the latter was the result of pressure build-up, a hydrogen explosion and, as Oehmen shows, the rupture of the containments within the plant, which drove molten core material into the local area. That’s the equivalent of what’s known as a ‘dirty bomb,’ and the main point of Oehmen’s article is that it’s not happening now in the Japanese reactors and it is not going to happen later.

I won’t go through the entire Fukushima situation here, but instead will send you directly to Oehmen’s essay, which was also reproduced on the BraveNewClimate site with a series of illustrations. But a few salient points: When the earthquake hit, the nuclear reactors went into automatic shutdown, with control rods inserted into the core and the nuclear chain reaction of the uranium stopped. The cooling system to carry away residual heat was knocked out by the tsunami, which destroyed the emergency diesel power generators, kicking in the battery backups, which finally failed when external power generators could not be connected.

This is the stage at which people began to talk about a core meltdown. Here is Oehmen on that scenario:

The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.

Nuclear After-Effects

So much for mushroom clouds over Fukushima. Oehmen’s article refers primarily to the Daiichi-1 reactor, but what is happening at Daiichi-3 seems to parallel the first reactor. He goes on to walk through the after-effects of all this, including the not inconsiderable issue that Japan will experience a prolonged power shortage, with as many as half of the country’s nuclear reactors needing inspection and the nation’s power generating capacity reduced by 15 percent. As to the effect of radiation in the environment:

Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.

I don’t want to minimize the effect of any of this (and I certainly don’t want to play down the pain, both physical and psychological, of the brave people of Japan), but at a time when terror over nuclear operations seems to be running rampant, it’s important that a more balanced view come to the fore in the media. In a message a few minutes ago (about 1330 UTC), Jason Morgan told me that the Oehmen essay would be posted soon on the MIT website, so I’ll link to that as soon as it goes up. Do read what Oehmen has to say as a counterbalance to the sensationalism that seems to follow nuclear issues whenever they appear, and help us keep a sane outlook on a very sad situation.

There are enough people in the population who think in binary terms that any amount of risk is equivalent to pending doom, and therefore RTG, nuclear power, or event getting on an airplane are unacceptable risks. This is amplified when combined with ignorance of science and the foundations of the technologies they use on a daily basis. That won’t change anytime soon, although this attitude is not universal.

With respect to the situation in Japan, it does seem that every expert I’ve heard speaking about the situation is not alarmed. The plants are well designed and they seem to have most every contingency covered, including dealing effectively and quickly with radiation releases. Even the explosions being reported are relatively benign and even expected if unwelcome due to the emergency cooling and venting procedures in play.

What is interesting is how much you invest to bring risk down to some vaguely appreciated level of uncertainty. For example, two things where the reactors in Japan appear to have hit their risk limits were:
– Designed to withstand 7.9 magnitude quakes.
– Emergency processes impacted by systemic effects; that is, much of the power grid is down so running machinery to effect containment and cooling using grid power (from other generators) was delayed.

The problem is how much additional money should be spent to lower the risk even further. This quickly gets into diminishing returns, so the expense is high for minimal improvement. The same is true of manned space flight, as we’ve seen numerous times.

Another lesson here, I think, is that the propulsion systems we often talk about in this forum contain enormous energies and require gargantuan containment and operations systems. With interstellar flight the magnitude is far greater. Even when we overcome the fundamental challenges of propulsion physics I suspect that far greater effort will go into channeling and managing the enormous energies involved to get the primary job done at an level of risk that is comparable to the nuclear energy industry. Just like in that previous article on anti-matter propulsion, even if we had lots of the stuff we have no way of using it effectively or safely.

While I didn’t read about Hiroshima style explosions, I did read about vented Cesium 137 and a possible core meltdown. The venting of cesium 137 may have been in small amounts and “fairly safe”, but do we have more than the authorities to back that up yet?

A core meltdown would have been more serious, although the article suggests that it would have been fully contained without contamination of the outside environment. Is that indeed the case, or would it have broken the containment? Even if there were no spill, and that the Japanese would clean up the containment structure, would the same be true in other countries if the situation were similar?

For space systems, the issue is surely the problem of catastrophic failure on launch. If such a fuss can be made over an RTG, a full scale reactor, e.g. to power a VASIMR ship, is orders of magnitude greater in damage on a launch failure. If we are to use reactors in space, they may need to be built there. Launchers fail, even unspectacularly with the Glory recent climate satellite.

The Japanese experience, if anything, should confirm that whatever safety precautions you want to design, you will be surprised and Murphy’s Law will also apply, unraveling those plans. While not against nuclear power, we should always be cognizant that we will be assured that “next time this won’t happen, because we’ve learned” and that a next time will happen.

I think nuclear power is finished in Europe. However, I don’t think this is the end of nuclear power in the U.S., much less Asia. It will definitely spur the development of better Gen IV technologies such as LFTR.

Actually, the more significant impact to nuclear power is coming from the recently discovered shale gas, which has turned the U.S. from a natural gas importer to a natural gas exporter. One the reasons for the recent cancellations of some of the new license applications for nuclear plants is due to the decreasing costs of natural gas.

There is lots of shale gas underneath Europe. I suspect Eastern China (the main part of China where everyone lives) also has huge reserves of shale gas. Why I think this is because the geology of this area is similar to our Mississippi river valley as well as that of Western Europe.

Another lesson here, I think, is that the propulsion systems we often talk about in this forum contain enormous energies and require gargantuan containment and operations systems. With interstellar flight the magnitude is far greater. Even when we overcome the fundamental challenges of propulsion physics I suspect that far greater effort will go into channeling and managing the enormous energies involved to get the primary job done at an level of risk that is comparable to the nuclear energy industry. Just like in that previous article on anti-matter propulsion, even if we had lots of the stuff we have no way of using it effectively or safely.

Centauri Dreams readers should memorize this paragraph — it’s an absolutely clear statement of a key propulsion issue that will become more and more significant as we push toward more ambitious missions.

“The plants are well designed and they seem to have most every contingency covered”

Except for the “flooding of the crucial backup generators necessary to run the cooling pumps” contingency, which as I understand it is the primary issue at the moment.

And frankly, any design that does not allow for passive safing of a reactor at loss of active cooling without any human input is simply not a good design. (Compare, for example, with some designs for molten salt reactors or uranium hydride reactors, which can be made inherently and passively safe with loss of coolant/loss of heat removal.)

These reactors are from the ’70s, and while their technology and designs may be excellent by the standards of the time, they don’t seem to me to be “well-designed”, especially given their location in an earthquake- and tsunami-prone region, where loss of cooling system (or at least flooding) would be a predictable outcome of a disaster.

I would also like to point out that risk is just a probability issue, but a control issue. We accept much higher levels of risk driving, because we feel we have some control over the risks. With other risks, e.g. nukes, we don’t feel we have any control, so we demand lower [perceived] risk levels. Thus if we launched a nuke for a spacecraft, and it failed, perhaps contaminating another country, the risk was neither wanted, or gained from, for the citizens of that country. With Chernobyl, the risk was not confined to Russia, but the radioactive plume crossed Scandinavia. While not serious, it wasn’t dismissible.

To keep the comparison playing field level, do recall that oil storage facilities in Japan caught fire, too (smoke is not risk free), and that even the design and construction of buildings (a seemingly benign technology) had good and bad lessons to share. And let’s not forget what BP did to the Gulf and that horrific pesticide plant accident (just chemical energy) in India many years ago, etc. Regardless, ALL technologies have risks and benefits and require responsible design and use. It appears that the nuclear facilities in Japan were designed well, and for that we should be grateful and get off the hype.

On another note, I completely agree with the statement from Ron S. that Paul echoed. For example, how many of you have ever noticed an absence of thermal radiators on science fiction vehicles?

As a son of a career nuclear Navy man, I say full speed ahead with continued developments of nuclear reactor technology. The U.S. Navy’s track record for reactor safety aboard its submarines and surface fleet is outstanding. The admission requirements for nuclear power training units that provide operators aboard the service’s submarine and aircraft carrier fleets are very high. Nuclear power can be safely utilized with proper training.

Add to the best reactor designs already utilized, the pebble bed reactor concept, and the proposed low power fusion source derived neutron nuclear fission initiation and we perhaps have a huge supply of fuel for our precursor interstellar manned missions.

I am also a fan of breeder reactor concepts because of the large quantities of breeder reactor feedstock within the Earth’s lithosphere, and presumably the same elsewhere, in all probability, ubiquitously throughout our cosmos.

Our civilization needs more nuclear energy based space propulsion system R&D and not less.

I have a special interest in low energy particle physics because related continuingly aquired knowledge will help us obtain every last bit of Isp we can obtain from fission fuel. Now if they can only find a reaction that has greater mass specific energy yield then hydrogen-! to helium fusion, that does not involve production of copious quantities of antimatter, that will be outstanding.

There has been far too much negative press and negative politics about nuclear energy, and it is high time that anti-nuclear energy activists realize that the nuclear genie never can be put back in the bottle.

Many folks unfortunately see nuclear energy as death itself, however, I see it as profoundly life oriented. Spreading human life ever further out into the cosmos is about a charitable as we can be by promoting the chance for untold potential human persons to have a chance to exist. Nuclear energy can be do our bidding here.

““The plants are well designed and they seem to have most every contingency covered”

Except for the “flooding of the crucial backup generators necessary to run the cooling pumps” contingency, which as I understand it is the primary issue at the moment.” -Tulse

That scenario was planned for as explained in the referenced article:
“When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.”

The article continues on from there. The system seems to have performed very well and the mistakes are more in not designing the power plants with a high enough factor of safety. Which is still a serious blunder that should not be taken lightly.

Something seems very odd about Japans nuclear crisis. Why go to all the expensive of backup diesel (and battery) generator, when these are complex enough for us to imagine them failing – as they did. Given that a secondary power supply is of such importance in cooling the core in an emergency power down, why wouldn’t it be much safer, if not cheaper, to have these power plants connected to a network of several other (diesel fired) power plants through a priority usage network of multiple redundant power line connections.

Another question that arises is: are deaths caused by psychological stress any less real that those due to other causes? Radioactivity can be measured in minute traces, and those who live in contaminated places, must chose whether to move out or stress over the ‘high’ levels of radiation.

Panic over low levels of ionising radiation could be particularly ironic if these turn out to actually reduce the risk of cancer. After all, low levels of uv light seem to reduce the risk of skin cancer, and I have heard that workers at nuclear power plants in the US have a significantly lower incidence of cancers than the general population.

I’m trying to understand what can happen in the case of meltdown of the core of the rector. So far I have not found anywhere a good description.
For example, moderating rods have been inserted and the reactor shut down.
However, residual heat and short term radioactive decay are still producing dangerous heat.
Now, I assume that, if the heat is not reduced (as they are trying with sea water), the uranium and moderating rods could melt and pool at the bottom of the containment vessel.
So far so good. At high temperature, both liquid , could the uranium and moderating material separate ? After all uranium is very heavy.
Once separated, could the nuclear reaction restart ?
I understand that there is not enough U235 for a nuclear explosion, but there’s enough for a sustained reaction. Is this correct ?
If a nuclear reaction is restarted, what stops the lump of melted uranium to melt through the containment vessel, the concrete etc. etc. ?
After all it self generates a lot of heat and can do that for long time, especially unmoderated.
I’m not worried about it making it to the center of the Earth because, even if it did, there’s plenty of radioactive stuff there. I’m more concerned about passing through the water table and spread contamination.

I’m not tying to be polemic, just want to understand. Is the above possible and if not why ?

Nuclear reactors always seem to draw all the attention when something goes wrong (and the term “meltdown” gets tossed all over the place in the media — which is a term that I’ve heard neither the IAEA nor the U.S. NRC have a definition for, by the way).

But I’d be curious to know how the net environmental damage caused by all nuclear accidents compares to the environmental damage caused by regular fossil fuel use (as well as accidents, like oil-spills). I think, for example, that mountaintop coal mining (where they blow up entire mountains to get at the coal) causes vast environmental damage beyond the scale that nuclear accidents have caused.

PS – If I remember correctly, I think the hysteria about Cassini’s RTGs was so great at one point that the mission controllers actually raised the altitude of it’s Earth Fly-by by a few hundred miles or so to alleviate the concern that it may re-enter our atmosphere and disperse it’s Plutonium across the globe…

As a son of a career nuclear Navy man, I say full speed ahead with continued developments of nuclear reactor technology….

Everywhere except for Europe.

And let’s not forget what BP did to the Gulf and that horrific pesticide plant accident (just chemical energy) in India many years ago, etc.

This was Union Carbide’s plant at Bhopal in 1983, which killed over 2,000 people. This disaster occurred because of the negligence of both Indian managers and the Indian government. Union Carbide’s management warned the Indian government when they built the plant not to allow people to live near it. The Indian government ignored the advice. The Indian government then insisted on Indian management control AFTER the plant was build. The Indian managers repeatedly ignored safety procedures that the Union Carbide’s managers repeatedly insisted on. The Bhopal disaster is a major reason why there will not be any direct foreign investment into India for the next 50 years. Foreign investors are not dumb enough to invest in industrial projects in India.

I seriously doubt that anywhere near 2,000 people will die as a result of the Fukushima Daiichi plant disaster.

Very discouraging to read this article, then turn around a few hours later and read this one: http://www.reuters.com/article/2011/03/14/us-japan-quake-rods-idUSTRE72D34S20110314, which claims in its title that the fuel rods at Fukushima are “fully exposed.” I’m no expert and don’t know if there is any possible justification for such a claim, but it does seem like the mainstream media is deliberately bending the truth to support its anti-nuclear agenda.

In my opinion one of the great unsolved mysteries of science is why coal typically contains such high quantities of radioactive nuclides. I wonder if any reader knows how much radioactivity these Japanese nuclear plants would have to release before they exceed the cumulative total of that dumped into the environment by Japanese coal fired stations. I remember one Scientific American article that claimed that US coal fired stations typically released 100x more radiation into the environment per kilowatt that nuclear ones. Even though this was not a true scientific paper, that surely should set us thinking.

My Dad had a career in journalism, and he often rants about how the current media lacks objectivism and honesty. It’s not as exciting to describe the nuclear reactors accurately and make an objective assessment of the damage. Bombastic, flashy news requires doom and destruction – and if you have to ignore science and facts, then so be it.

This concerns me because I see nuclear power as a great development that should continue. It has enormous potential for not only power on earth, but as you rightly pointed out, in space. Missions out to gas giant territory will recieve little solar power, so nuclear power or derivations thereof will be needed. In the long term, space colonies further out will be highly reliant on nuclear power.

In the context of this article the actions and the words of the Japanese government seem rather puzzling. For example, today’s The Wall Street Journal reports:

“Prime Minister Naoto Kan gave a brief address to the nation saying, ‘The level [of radiation] seems very high, and there is still a very high risk of more radiation coming out.’

‘We will do our utmost to prevent further spreading of radiation leaks,’ he said. ‘I sincerely urge everyone in the nation to act calmly.’

Mr. Kan, wearing the blue jumpsuit uniform for emergency workers, added that ‘the risk of further increases in radiation leaks to surrounding areas is rising.’ He said that anyone within 18 miles of the plant should stay indoors. Previously the government had said people living within 12 miles should evacuate.”

What leaks, what spreading, what 12 miles, what “very high level of radiation”? Is he misinformed or misinterpreted? Or maybe this Oehmen’s article is actually misleading saying that it’s no big deal?

The greatest damage done by this nuclear accident in Japan might well appear to be the setback it is likely to do to further nuclear development, including the development and deployment of inherently safe, plus more efficient reactors plus enhanced recycling of spent nuclear fuel, especially here in Europe. It may even promote the use of and reversal to coal fired power plants. A sad irony. But politics and public perception (read: panic) usually dominate decision making and prevail over common sense and vision.
What kurt9 says is also relevant here: natural gas and increasingly the exploitation of shale gas is becoming more and more important and as a result of this accident will likely just become a greater competitor for nuclear.
kurt9: from what I have understood the geology with regard to shale gas is somewhat different in most of Europe, the shale gas deposits being more scattered, which may be a reason (besides abundant cheap natgas from Russia) why shale gas is still (much) less developed in Europe. But it will undoubtedly come here as well.

If Europe abandons nuclear power, they will definitely work to develop their shale gas. Either that or rely on Mr. Putin and his associates for their electricity. China has lots of shale oil as well. Japan has its gas hydrates just off-shore.

Thorium is a by-product of the mining of rare-earth metals. I believe it is also rather concentrated in coal ash. It means we get the Thorium for free in both cases. Think of both activities as the first processing step for the fuel for Thorium-powered reactors. I really think we need to develop the Gen IV nuclear power reactors, especially the LFTR.

Even in consideration of any risks that current modern nuclear fission reactors might have, the process of nuclear fission power plant R&D is far from complete.

For instance, fusion source neutron catalyzed nuclear fission offers the possibility of doing nuclear fission based power generation with perhaps up to 99.8 percent radioactive waste burnup without removing the fuel from the reactor. Such reactors could be inherently sub-critical when the fusion neutron source is shut down such as for maintanence activities or system failure.

Personally, I enjoy reading about nuclear fission and at one point during the 1980s, I considered applying to a university that has a nuclear engineering program. The stuff is just plain enjoyable and even more fun in the context of star ship propulsion.

I agree with people freaking out with sensationalism. However, in this article one factor that was taken for granted was that the plants’ steel containment units around the cores would not be breached by a hydrogen explosion. But, last night it appears one of them was in fact breached by the latest explosion(the third one)…and another factor that was not even considered was the possibility of the spent rods being stored next to the reactors, with their containment units being blown off and the pools then set ablaze…

So yes, no mushroom clouds, but the possibility of radioactive contamination appears rather high at this point. And above levels that would normally be considered safe, even by grizzled nuclear safety folk standards.

So I suppose we have to also combat our own biases here, being pro-nuclear, for reasons practical and fun.

@kurt9
Nuclear power could be finished in Germany, where people seem most hysterical about it, but it will not be finished in France, since over 75% of all electricity is nuclear there.
@Enzo
I think you might be mixing 2 concepts there, moderator (water, usually) slows down (moderates) neutrons and as such makes them more likely to cause fissions, neutron absorbers (or “neutron poison”s) capture neutrons and as such they preclude neutrons from causing fission. The control rods are neutron absorbers.

As the disaster of the magnitude 8.9 Sendai quake of Friday, March 11, at 05:46:23 UTC continues to unfold in Japan, I have been unable to tear my attention away. Over the weekend I’ve heard much good news about the safety of many friends there, among residents, visitors, and facilities, but also much that is horrifying about the scale and far-reaching effects of just one quake on one fault among many thousands of faults that cut Earth’s crust into interlocking pieces. I can’t bear to watch the endless videos of the earthquake and tsunami’s acts of destruction; I shy away from the cost in lives and property that each image evidences. I send my wishes for the safety of those I haven’t heard from, and for all of Japan’s recovery from this unimaginable disaster.

Even as my mind turns away from the human cost, I am fascinated by the geophysical observations. It’s a terrible tragedy but one that we can learn from. Hopefully we here in America can learn enough from it to implement some protections in time for the next Big One that hits Los Angeles, or San Francisco, or Seattle. It’s not lost on me that we are nowhere near as prepared as Japan was — to see such a modern and forward-looking society as Japan struggling to cope with the earthquake is frightening.

As I can’t seem to stop thinking about the earthquake I thought I would try to gather some links to the geophysical reports that I’ve found most informative. But before I do that, let me share some of what I’ve learned about space people and facilities affected by the quake.

Three days after a catastrophic earthquake and tsunami hit Japan, the situation at the Fukushima Dai-ichi nuclear complex has turned into the biggest uncertainty of the crisis. Recovering from the seismic event will take tens of billions of dollars and years of work — but if the nuclear situation goes the wrong way, that would add dramatically to the disaster’s cost.

How did all this happen, and how could it end? Different folks have different answers, depending on how they feel about nuclear power. Here’s a roundup of the best answers I’ve been able to put together — accompanied by an invitation to add your own sources and perspectives as comments below:

Disney certainly knew how to make learning interesting at the least. And despite the current crisis in Japan, I still think nuclear energy will go a long to sustaining our technological civilization and getting us to the stars.

Many of those who protested Cassini back in 1997 showed themselves to be far more biased against nuclear power than terribly knowledgable about it or the fact that the RTGs on the probe could withstand an explosion of the rocket plus the plunge back to Earth.

I distinctly recall one anti-nuker on the Web who wanted to crash Cassini into Venus during its flyby of that planet on its way to Saturn because, according to him, Venus has no atmosphere! Hard to take such folks seriously. I also recall a friend telling me he went to a meeting about Cassini in Cambridge, MA. He was the only pro-space person there and the others told him they had already made up their minds about the space probe and did not want to hear any facts on the subject. Has Harlan Ellison once said, everyone is entitled to espouse an INFORMED opinion.

The Planetary Society blog posted this article by an American who was at a planetary science conference in Japan when the earthquake struck:

As Japan’s Fukushima power plant continues to struggle with massive equipment failure and radiation release that could well reach Chernobyl levels, we can take some small comfort in the knowledge that a full-on nuclear explosion is completely impossible. Here’s why:

WOW. That should have been a straight forward swap. Also, if they had 8 hours of battery, why did they wait for water to boil off and radiation to become an issue, before bringing in fire trucks, helicopters and pumping in sea water? Sounds to me like nobody made tough decisions. (Yes it will damage the plant, but prevent possibly deadly radiation.) We can certainly learn from this when making starships.

What physically cannot be don, will not be done. However the extremely dedicated employees’ work can still make a difference, and the effect of this disaster on all of us is still going to be influenced by the success of their mission.

I salute to them trying to save Japan, and to a certain extent, the world from the horrible effects of the radiation. Check out this powerful video on youtube, dedicate to these people on whom, to a tiny or to a larger degree, our health depends:

Small amounts of radioactive material have turned up in rainwater in the Bay Area, say nuclear scientists

kfc 04/01/2011

Last week, we looked at evidence gathered in Seattle of tiny amounts of radioactive material that had made its way across the Pacific from the stricken nuclear reactors in Fukushima, Japan.

So it’s no surprise that similar evidence is turning up further down the coast in San Francisco.

Between 16 and 26 March, Eric Norman and pals at the department of nuclear engineering at UC Berkeley placed buckets at various locations in the Bay Area to gather rain water (the earthquake that triggered the accident occurred on 11 March). They then analysed the water they collected, looking for the tell tale gamma rays from radioactive stuff.

As expected, they found it. “Gamma ray spectra measured from these samples show clear evidence of fission products – iodine-131 and132, tellurium-132 and cesium-134 and 137,” say Norman and co.

Radioactive byproducts indicate that nuclear chain reactions must have been burning at the damaged nuclear reactors long after the disaster unfolded

kfc 05/09/2011

Nuclear reactors produce radioactive by-products that decay at different rates. One common by-product is iodine-131 which has a half life of about 8 days while another is cesium-137 with a half life of about 30 years.

When a reactor switches off, the iodine decays more quickly so the ratio between these two isotopes changes rapidly over a period of days. That’s why measuring this ratio is a good way to work out when the nuclear reactions terminated.

There are some complicating factors, however. The most important of these is that the ratio of iodine-131 and cesium-137 to start with depends on how long the reactor has been operating and so is not constant.

That’s because, after a reactor has been switched on, the levels of iodine-131 reach an equilibrium on a timescale similar to its half life of about 8 days.

But cesium-137, with a half life of 30 years, takes much longer to reach equilibrium. To all intents and purposes, the levels of cesium-137 in a reactor continue to grow steadily during the timescales over which reactors are usually operated.

The Fukushima reactor was struck by a magnitude 9 earthquake at 14:46 local time on 11 March. The three operating reactors there were immediately shut down.

About an hour later, however, the facility was struck by a tsunami with waves up to 5 meters in height. This destroyed the reactors’ electric cooling ability and the reactors began to heat up. The reaction between water vapour and the nuclear fuels’ zirconium cladding generated hydrogen which exploded in reactors 1, 3 and 4.

The question on many people’s minds is whether the hot nuclear fuel then melted allowing a critical mass of molten fuel to form, allowing chain reactions to restart.

Today, Tetsuo Matsui at the University of Tokyo, says the limited data from Fukushima indicates that nuclear chain reactions must have reignited at Fuksuhima up to 12 days after the accident.

Matsui says the evidence comes from measurements of the ratio of cesium-137 and iodine-131 at several points around the facility and in the seawater nearby. He has calculated what the starting ratio must have been by assuming the reactors had been operating for between 7 and 12 months.

He says the ratios from drains at reactors 1 and 3 at Fukushima are consistent with the nuclear reactions having terminated at the time of the earthquake.

However, the data from the drain near reactor 2 and from the cooling pond at reactor 4, where spent fuel rods are stored, indicate that the reactions must have been burning much later.

“The data of the water samples from the unit-4 cooling pool and from the sub-drain near the unit-2 reactor show anomaly which may indicate, if they are correct, that some of these ﬁssion products were produced by chain nuclear reactions reignited after the earthquake,” he says.

These chain reactions must have occurred a significant time after the accident. “It would be diﬃcult to understand the observed anomaly near the unit-2 reactor without assuming that a signiﬁcant amount of ﬁssion products were produced at least 10 – 15 days after X-day,” says Matsui.

So things in reactor 2 must have been extremely dangerous right up to the end of March.

Matsui points out that there are some potential question marks about the data. One possibility is that the chemical properties of cesium and iodine might mean they are flushed away from the reactors at different rates, changing their ratios.

But it’s hard to see what chemical processes could be responsible for this and even harder to understand why they would occur in some places but not others at Fukushima.

Of course, it won’t be possible to determine exactly what went on in reactor 2 and in the spent fuel ponds at reactor 4 until the sites can be physically examined in detail.

But in the meantime, Matsui’s analysis gives us one of the best insights so far into the nature of the disaster that unfolded after the tsunami hit.

Infrared emissions above the epicenter increased dramatically in the days before the devastating earthquake in Japan, say scientists.

kfc 05/18/2011

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Geologists have long puzzled over anecdotal reports of strange atmospheric phenomena in the days before big earthquakes. But good data to back up these stories has been hard to come by.

In recent years, however, various teams have set up atmospheric monitoring stations in earthquake zones and a number of satellites are capable of sending back data about the state of the upper atmosphere and the ionosphere during an earthquake.

Last year, we looked at some fascinating data from the DEMETER spacecraft showing a significant increase in ultra-low frequency radio signals before the magnitude 7 Haiti earthquake in January 2010

Today, Dimitar Ouzounov at the NASA Goddard Space Flight Centre in Maryland and a few buddies present the data from the Great Tohoku earthquake which devastated Japan on 11 March. Their results, although preliminary, are eye-opening.

They say that before the M9 earthquake, the total electron content of the ionosphere increased dramatically over the epicentre, reaching a maximum three days before the quake struck.

At the same time, satellite observations showed a big increase in infrared emissions from above the epicentre, which peaked in the hours before the quake. In other words, the atmosphere was heating up.

These kinds of observations are consistent with an idea called the Lithosphere-Atmosphere-Ionosphere Coupling mechanism. The thinking is that in the days before an earthquake, the great stresses in a fault as it is about to give cause the releases large amounts of radon.

The radioactivity from this gas ionises the air on a large scale and this has a number of knock on effects. Since water molecules are attracted to ions in the air, ionisation triggers the large scale condensation of water.

But the process of condensation also releases heat and it is this that causes infrared emissions. “Our first results show that on March 8th a rapid increase of emitted infrared radiation was observed from the satellite data,” say Ouzounov and co.

These emissions go on to effect the ionosphere and its total electron content.

It certainly makes sense that the lithosphere, atmosphere and ionosphere are coupled in a way that can be measured when one of them is perturbed. The question is to what extent the new evidence backs up this idea.

The Japan earthquake is the largest to have struck the island in modern times and will certainly turn out to be among the best studied. If good evidence of this relationship doesn’t emerge from this data, other opportunities will be few and far between.

50 Years of Nuclear-Powered Spacecraft: It All Started with Satellite Transit 4A

by Leonard David, SPACE.com’s Space Insider Columnist

Date: 29 June 2011 Time: 04:51 PM ET

Consider this a nuclear blast from the past – all the way back to the early days of U.S. space missions, when the first satellite to use a radioactive power source launched into orbit.

The satellite, called Transit 4A, launched on June 29, 1961 atop a Thor-DM21 Able-Star rocket. The drum-shaped spacecraft weighed only 175 pounds and was laden with solar cells tied to nickel-cadmium batteries.

Fifty years ago, the Transit 4A satellite marked the first flight test of a nuclear power source developed for use in spacecraft. The repercussions stemming from this early satellite now stretch out throughout our known solar system … and beyond.

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last twelve years, this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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